Merge pull request #1268 from pacu/dbz-mitigation

Sources/ZcashLightClientKit/Model/ScanProgress.swift

@@ -12,8 +12,11 @@ struct ScanProgress: Equatable {
     let denominator: UInt64
     
     func progress() throws -> Float {
-        // division by 0 is not a concern here because `ZcashRustBackend.getScanProgress() -> ScanProgress?`
-        // handles the 0 and returns nil rather than returning nil progress or 0 value here
+        guard denominator != 0 else {
+            // this shouldn't happen but if it does, we need to get notified by clients and work on a fix
+            throw ZcashError.rustScanProgressOutOfRange("\(numerator)/\(denominator)")
+        }
+
         let value = Float(numerator) / Float(denominator)
         
         // this shouldn't happen but if it does, we need to get notified by clients and work on a fix

Tests/OfflineTests/ZcashRustBackendTests.swift

@@ -157,4 +157,14 @@ class ZcashRustBackendTests: XCTestCase {
         XCTAssertEqual(metadata?.networkType, .mainnet)
         XCTAssertEqual(metadata?.addressType, .sapling)
     }
+
+    func testScanProgressThrowsOnWrongValues() {
+        // Assert that throws on Zero denominator
+        XCTAssertThrowsError(try ScanProgress(numerator: 0, denominator: 0).progress())
+
+        // Assert that throws on numerator > denominator
+        XCTAssertThrowsError(try ScanProgress(numerator: 23, denominator: 2).progress())
+
+        XCTAssertNoThrow(try ScanProgress(numerator: 3, denominator: 4).progress())
+    }
 }